/Engine/Source/Editor/UMGEditor/Public/WidgetBlueprintEditor.h
Gets external widget whose lifetime should be managed by this editor, NullWidget if not found
[TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< [SWidget](API\Runtime\SlateCore\Widgets\SWidget) > GetExternalEditorWidget ( [FName](API\Runtime\Core\UObject\FName) ID )